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• Building a livestream page where the user will input an rtsp streaming source through an ip address

  7 décembre 2020, par Antax Md

  I am building a livestream page where the streaming source is streamed through rtsp. Currently, I am using ffmpeg to convert the incoming rtsp stream to a .m3u8 file and it is played back on the webpage through HLS.

  


  The problem i am trying to solve now, is loading an rtsp stream based on the user's input. How do i go about solving this ? It is a requirement to able to view the stream on iOS and android.
The ffmpeg command :

  


  ffmpeg -i "rtsp://10.193.79.185:5554" -hls_time 3 -hls_wrap 10 "C:\wamp64\www\hls\output.m3u8"


  


  Code of what I have at the moment that loads a hard coded rtsp stream

  


  &#xA;&#xA;  &#xA;      <code class="echappe-js">&lt;script src=&quot;https://cdn.jsdelivr.net/npm/hls.js@latest&quot;&gt;&lt;/script&gt;&#xA;      &#xA;          
  RTSP Stream
  &#xA;                &#xA;                &#xA;
  Start
  &#xA;                &#xA;
  
  &#xA;      &#xA;&#xA;      &lt;script&gt;&amp;#xA;        if(Hls.isSupported()) &amp;#xA;        {&amp;#xA;            var video = document.getElementById(&amp;#x27;video&amp;#x27;);&amp;#xA;            var mystring = &quot;http://192.168.43.79/hls/output.m3u8&quot;;&amp;#xA;            var hls = new Hls({&amp;#xA;              debug: true&amp;#xA;            });&amp;#xA;            hls.loadSource(mystring);&amp;#xA;            hls.attachMedia(video);&amp;#xA;            hls.on(Hls.Events.MEDIA_ATTACHED, function() {&amp;#xA;            video.muted = true;&amp;#xA;            video.play();&amp;#xA;        });&amp;#xA;        }&amp;#xA;        // hls.js is not supported on platforms that do not have Media Source Extensions (MSE) enabled.&amp;#xA;        // When the browser has built-in HLS support (check using `canPlayType`), we can provide an HLS manifest (i.e. .m3u8 URL) directly to the video element throught the `src` property.&amp;#xA;        // This is using the built-in support of the plain video element, without using hls.js.&amp;#xA;        else if (video.canPlayType(&amp;#x27;application/vnd.apple.mpegurl&amp;#x27;)) {&amp;#xA;            video.src = &amp;#x27;http://192.168.43.79/hls/output.m3u8&amp;#x27;;&amp;#xA;            video.addEventListener(&amp;#x27;canplay&amp;#x27;,function() {&amp;#xA;            video.play();&amp;#xA;          });&amp;#xA;        }&amp;#xA;      &lt;/script&gt;&#xA;  &#xA;&#xA;
  

  


• Up-mix Stereo to 5.1 with FFMPEG, filtering each channel [closed]

  2 octobre 2020, par Jim

  I developed this to transform stereo to 5.1 :

  


  ffmpeg -i d:\man.mp4 -c:v mpeg2video -b:v 8M -maxrate 12M -bufsize 4M -filter_complex "pan=5.1|FL=FL|FR=FR|FCcode>

  


  Note : this also does an mp4 to mpeg2 conversion

  


  The issue is that the dialog is on all the channels and it doesn't sound like real 5.1. What I would like to do is apply a bandpass filter to just the center channel to focus on the dialog piece. I then want to apply an opposite notch filter to the rest of the channels to focus on everything but the dialog.

  


  Been doing a lot of searching and coming up empty. Many thanks for a nudge in the right direction.

  


• Reverse Engineering Radius VideoVision

  3 avril 2011, par Multimedia Mike — Reverse Engineering

  I was called upon to help reverse engineer an old video codec called VideoVision (FourCC : PGVV), ostensibly from a company named Radius. I’m not sure of the details exactly but I think a game developer has a bunch of original FMV data from an old game locked up in this format. The name of the codec sounded familiar. Indeed, we have had a sample in the repository since 2002. Alex B. did some wiki work on the codec some years ago. The wiki mentions that there existed a tool to transcode PGVV data into MJPEG-B data, which is already known and supported by FFmpeg.

  The Software
  My contacts were able to point me to some software, now safely archived in the PGVV samples directory. There is StudioPlayer2.6.2.sit.hqx which is supposed to be a QuickTime component for working with PGVV data. I can’t even remember how to deal with .sit or .hqx data. Then there is RadiusVVTranscoder101.zip which is the tool that transcodes to MJPEG-B.

  Disassembling for Reverse Engineering
  Since I could actually unpack the transcoder, I set my sights on that. Unpacking the archive sets up a directory structure for a component. There is a binary called RadiusVVTranscoder under RadiusVVTranscoder.component/Contents/MacOS/. Basic deadlisting disassembly is performed via ’otool’ as shown :

    otool -tV RadiusVVTranscoder | c++filt
  

  This results in a deadlisting of both PowerPC and 32-bit x86 code, as the binary is a "fat" Mac OS X binary designed to run on both architectures. The command line also demangles C++ function signatures which gives useful insight into the parameters passed to a function.

  Pretty Pictures
  The binary had a lot of descriptive symbols. As a basis for reverse engineering, I constructed call graphs using these symbols. Here are the 2 most relevant portions (click for larger images).

  The codec initialization generates Huffman tables relevant to the codec :

  
  
  

  The main decode function calls AddMJPGFrame which apparently does the heavy lifting for the transcode process :

  
  
  

  Based on this tree, I’m guessing that luma blocks can be losslessly transcoded (perhaps with different Huffman tables) which chroma blocks may rely on a different quantization method.

  Assembly Constructs
  I started looking at the instructions (the x86 ones, of course). The binary uses a calling convention I haven’t seen before, at least not for the x86 : Rather than pushing function arguments onto the stack, the code manually subtracts, e.g., 12 from the ESP register, loads 3 32-bit arguments into memory relative to ESP, and then proceeds with the function call.

  I’m also a little unclear on constructs such as "call ___i686.get_pc_thunk.bx" seen throughout relevant functions such as MakeRadiusQuantizationTables().

  I’m just presenting what I have so far in case anyone else wants to try their hand.